The present invention pertains to apparatus and methods for monitoring a condition of a tire, and more particularly to apparatus and methods for monitoring a condition of a pneumatic tire.
In order to transport bulk materials, such as coal, iron ore and other minerals, the mining industry uses Off-The-Road (OTR) vehicles that can weigh over 600 tons when fully loaded, with the result that exceedingly high internal stresses are imposed on the tires of such vehicles in the course of their daily use. These internal stresses, which are attributable to a number of factors including driving at excessive speeds, are so destructive of such tires that it is not uncommon to have to replace the tires. On the other hand, in order to maximize the productivity of OTR vehicles, they are normally driven as fast as possible until a user perceives that the internal physical condition of any given tire is marginal. Whereupon, the operator either stops, in the case of a loss of tire pressure, or reduces the speed of the vehicle, in the case of an excessive temperature condition, to relieve the internal stresses giving rise to the marginal condition and thereby prolonging the life of the tires. Thus the speed of an OTR vehicle is controlled on the basis of the operator""s perception of the condition of the tires at any given time. And, if the operator""s perception is erroneous, the productivity of the vehicle is unnecessarily reduced.
Accordingly, a long-standing need of the mining industry has been to ensure that the operators of OTR vehicles are provided with accurate information concerning various conditions of the tires of such vehicles, with a view to maximizing the productivity of the vehicles.
Various attempts have been made in the prior art to meet the aforesaid need, most recently by mounting integrated circuits within each of the tires of an OTR vehicle, for detecting respective conditions related to an imminent failure of each tire and providing the OTR vehicle operators with timely information concerning such conditions. These integrated circuits have been generally referred to as xe2x80x9ctire tagsxe2x80x9d and have been mounted to the interior surface of the tire. One such tire tag is described in U.S. Pat. No. 6,255,940, assigned to the assignee of the present invention and incorporated herein by reference in its entirety. The tag includes a patch comprising vulcanized rubber, which serves as a mounting base for attaching the tag to a tire""s inner liner by cementing the patch to the inner liner.
While prior tire tags have addressed the need for providing information regarding the condition of a tire to its users, these tags suffer several drawbacks. For example, the prior tire tags require additional preparation time and effort to buff and clean an area of the inner surface of the tire where the patch will be adhered to the interior of the tire. Furthermore, the location of the tire tag on the interior surface of the tire causes the tag to be exposed to liquid tire fill which is commonly added to OTR wheels to help prevent corrosion of the wheels. This is particularly problematic when the vehicle is stopped and the wheel is in an orientation which places the tire tag at the bottom-most location of the wheel such that it is submerged beneath the liquid fill material.
There is thus a need for an apparatus for monitoring the condition of a tire which overcomes drawbacks of the prior art, such as those described above.
The present invention provides a sensor which may be readily secured within the interior of a vehicle wheel to monitor the condition of a tire mounted to the wheel rim and which avoids sustained exposure to liquid fill material which may be added within the tire. In this regard, the sensor is configured to be mounted to the wheel rim instead of an inner liner of the tire. Accordingly, the sensor does not require the preparation and cleaning associated with securing conventional tire tags to the inner liner of the tire. Advantageously, the sensor will not be submerged beneath liquid fill material which may be added to the tire, even when the wheel is oriented with the sensor positioned at a lower-most location of the rim.
In one aspect, the sensor is secured to a circumferential surface of the wheel rim by at least one strap that extends around the rim. The sensor may include a base which facilitates securing the sensor to the wheel rim. In another aspect, the base includes one or more notches configured to receive the strap.
In yet another aspect of the invention, a temperature sensing component is embedded within a casing of the sensor, near an outer surface of the sensor, and is coupled to a conductor which extends from the surface of the sensor. Advantageously, this arrangement enables the temperature sensing component to sense a temperature that is more directly related to the average air temperature of the volume of air contained within the tire cavity.
In another aspect of the invention, an instrumented wheel includes a wheel rim, a sensor configured for installation within the interior of a vehicle wheel, and securing structure configured to affix the sensor to the rim of the wheel.
In another aspect of the invention, a method of securing a tire sensor within the interior of a vehicle wheel includes positioning the sensor at a desired location on a rim of the wheel and securing the sensor to the rim.
The features and objectives of the present invention will become more readily apparent from the following Detailed Description taken in conjunction with the accompanying drawings.